How to dress: split maxi dresses

Here's the thing about celebrity fashion: you will learn nothing about clothes by looking at a photo of Angelina Jolie in a dress. Because, however lovely the dress, the dress is not the point. It's like watching Rain Man for tips on mental arithmetic. Or interpreting Botticelli's The Birth of Venus as a how-to guide to beach chic (Rapunzel-length hair and a giant seashell, right?). There is simply no useful information to be parsed from an image of Angie in a frock. And yet we do look, and it seems we are influenced. Because while Angelina's Oscar frock – floorlength black, with a deep split revealing a long pale thigh – was something of a Marmite choice on the red carpet, it is evolving into a bread-and-butter basic on the high street as the summer collections hit their stride. Whereas once the split maxi was a niche item for that small section of the population whose social life regularly calls for a "gown", the day-to-night maxi dresses that make their way into the wardrobes of us norms have developed show-off splits of their own. This summer, a maxi dress isn't complete without a to-the-thigh slit. When you put that split in a floor-length dress, you change its nature. A maxi dress without a split is serene, innocent, bohemian and outdoorsy: a dress for making daisy chains, lying on the grass. Whereas a maxi dress with a split is for perching on bar stools, and the closest you'll be getting to nature is an elderflower martini. A split in a dress gives it a vixenish air, one that, like Strictly Come Dancing and Liz Hurley, is slightly camp in a rather British way. The vixen can be tamed, however, by not doing the leg-thrust. The occasional non-thrusting glimpse of leg serves as a reminder that you are, in fact, a woman, not a mushroom, which can only be a good thing. That is the most you should use the split for: it's not a theatre curtain, after all. The leg thrust has become a signature red-carpet move by female celebrities who favour this style of dress. Paul McCartney has his thumbs-up ; Liz Hurley has the flex-and-pivot knee. Angelina has, well, Angelina is Angelina. She's irrelevent. Remember that. • Jess wears maxi dress , £75, by Warehouse . Shoes , £39.99, by Zara . Hair and make-up: Jen Fechter.